Detailed Abundances in the Galactic Center: Evidence of a Metal-rich Alpha-enhanced Stellar Population

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We present a detailed study of the composition of 20 M giants in the Galactic center with 15 of them confirmed to be in the nuclear star cluster. As a control sample we have also observed 7 M giants in the Milky Way disk with similar stellar parameters. All 27 stars are observed using the NIRSPEC spectrograph on the KECK II telescope in the K-band at a resolving power of R = 23,000. We report the first silicon abundance trends versus [Fe/H] for stars in the Galactic center. While finding a disk/bulge-like trend at subsolar metallicities, we find that [Si/Fe] is enhanced at supersolar metallicities. We speculate on possible enrichment scenarios to explain such a trend. However, the sample size is modest and the result needs to be confirmed by additional measurements of silicon and other α-elements. We also derive a new distribution of [Fe/H] and find the most metal-rich stars at [Fe/H] = +0.5 dex, confirming our earlier conclusions that the Galactic center hosts no stars with extreme chemical compositions.


Enheter & grupper
Externa organisationer
  • University of California, Los Angeles
  • Laboratoire Joseph-Louis Lagrange
  • Aarhus University
  • Instituto de Astrofísica de Canarias
  • University of La Laguna (ULL)
  • INAF Istituto di Astrofisica Spaziale e Fisica Cosmica, Bologna
  • University of Trieste
  • INAF Astronomical Observatory of Trieste
  • INFN Sezione di Trieste
  • CSIC Instituto de Astrofísica de Andalucía (IAA)

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Astronomi, astrofysik och kosmologi
TidskriftAstrophysical Journal
Utgåva nummer1
StatusPublished - 2020
Peer review utfördJa